[patch 14/14] boot cputime accounting

Martin Schwidefsky
2009-04-14T13:53:41Z

[-- Attachment #1: 014-boot-cputime.diff --]
[-- Type: text/plain, Size: 5465 bytes --]

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Start the cpu time accounting very early to catch the cpu time spent
for the initial kernel setup. To make the output of /proc/uptime
match the sum of all cpu accounting values of the boot cpu reset
xtime and wall_to_monotonic to sane values based on the TOD clock.
The values set by timekeeping_init are off by up to a second.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

arch/s390/kernel/head.S | 8 +++++++-
arch/s390/kernel/setup.c | 8 ++++++++
arch/s390/kernel/time.c | 36 ++++++++++++++++++++++++++++--------
arch/s390/kernel/vtime.c | 8 --------
4 files changed, 43 insertions(+), 17 deletions(-)

Index: quilt-2.6/arch/s390/kernel/head.S
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/head.S
+++ quilt-2.6/arch/s390/kernel/head.S
@@ -473,7 +473,10 @@ startup:basr %r13,0 # get base
xc 0x300(256),0x300
l %r1,5f-.LPG0(%r13)
stck 0(%r1)
-
+ spt 6f-.LPG0(%r13)
+ mvc __LC_LAST_UPDATE_CLOCK(8),0(%r1)
+ mvc __LC_LAST_UPDATE_TIMER(8),6f-.LPG0(%r13)
+ mvc __LC_EXIT_TIMER(8),5f-.LPG0(%r13)
#ifndef CONFIG_MARCH_G5
# check processor version against MARCH_{G5,Z900,Z990,Z9_109,Z10}
stidp __LC_CPUID # store cpuid
@@ -500,8 +503,11 @@ startup:basr %r13,0 # get base

l %r13,4f-.LPG0(%r13)
b 0(%r13)
+ .align 4
4: .long startup_continue
5: .long sched_clock_base_cc
+ .align 8
+6: .long 0x7fffffff,0xffffffff

#
# params at 10400 (setup.h)
Index: quilt-2.6/arch/s390/kernel/setup.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/setup.c
+++ quilt-2.6/arch/s390/kernel/setup.c
@@ -434,6 +434,14 @@ setup_lowcore(void)
#else
lc->vdso_per_cpu_data = (unsigned long) &lc->paste[0];
#endif
+ lc->sync_enter_timer = S390_lowcore.sync_enter_timer;
+ lc->async_enter_timer = S390_lowcore.async_enter_timer;
+ lc->exit_timer = S390_lowcore.exit_timer;
+ lc->user_timer = S390_lowcore.user_timer;
+ lc->system_timer = S390_lowcore.system_timer;
+ lc->steal_timer = S390_lowcore.steal_timer;
+ lc->last_update_timer = S390_lowcore.last_update_timer;
+ lc->last_update_clock = S390_lowcore.last_update_clock;
set_prefix((u32)(unsigned long) lc);
lowcore_ptr[0] = lc;
}
Index: quilt-2.6/arch/s390/kernel/time.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/time.c
+++ quilt-2.6/arch/s390/kernel/time.c
@@ -253,32 +253,52 @@ void update_vsyscall_tz(void)
*/
void __init time_init(void)
{
+ struct timespec ts;
+ unsigned long flags;
+ cycle_t now;
+
/* Reset time synchronization interfaces. */
etr_reset();
stp_reset();

- /* set xtime */
- tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &xtime);
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
-
/* request the clock comparator external interrupt */
if (register_early_external_interrupt(0x1004,
clock_comparator_interrupt,
&ext_int_info_cc) != 0)
panic("Couldn't request external interrupt 0x1004");

- if (clocksource_register(&clocksource_tod) != 0)
- panic("Could not register TOD clock source");
-
/* request the timing alert external interrupt */
if (register_early_external_interrupt(0x1406,
timing_alert_interrupt,
&ext_int_etr_cc) != 0)
panic("Couldn't request external interrupt 0x1406");

+ if (clocksource_register(&clocksource_tod) != 0)
+ panic("Could not register TOD clock source");
+
+ /*
+ * The TOD clock is an accurate clock. The xtime should be
+ * initialized in a way that the difference between TOD and
+ * xtime is reasonably small. Too bad that timekeeping_init
+ * sets xtime.tv_nsec to zero. In addition the clock source
+ * change from the jiffies clock source to the TOD clock
+ * source add another error of up to 1/HZ second. The same
+ * function sets wall_to_monotonic to a value that is too
+ * small for /proc/uptime to be accurate.
+ * Reset xtime and wall_to_monotonic to sane values.
+ */
+ write_seqlock_irqsave(&xtime_lock, flags);
+ now = get_clock();
+ tod_to_timeval(now - TOD_UNIX_EPOCH, &xtime);
+ clocksource_tod.cycle_last = now;
+ clocksource_tod.raw_time = xtime;
+ tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &ts);
+ set_normalized_timespec(&wall_to_monotonic, -ts.tv_sec, -ts.tv_nsec);
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+
/* Enable TOD clock interrupts on the boot cpu. */
init_cpu_timer();
+
/* Enable cpu timer interrupts on the boot cpu. */
vtime_init();
}
Index: quilt-2.6/arch/s390/kernel/vtime.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/vtime.c
+++ quilt-2.6/arch/s390/kernel/vtime.c
@@ -527,16 +527,8 @@ EXPORT_SYMBOL(del_virt_timer);
*/
void init_cpu_vtimer(void)
{
- struct thread_info *ti = current_thread_info();
struct vtimer_queue *vq;

- S390_lowcore.user_timer = ti->user_timer;
- S390_lowcore.system_timer = ti->system_timer;
-
- /* kick the virtual timer */
- asm volatile ("STCK %0" : "=m" (S390_lowcore.last_update_clock));
- asm volatile ("STPT %0" : "=m" (S390_lowcore.last_update_timer));
-
/* initialize per cpu vtimer structure */
vq = &__get_cpu_var(virt_cpu_timer);
INIT_LIST_HEAD(&vq->list);